[bhushan4work]

Add the Welcome newsletter template (newsletter-welcome) with expectations and sign-off.

Closes #247

Description

Adds a newsletter welcome template with a customizable label, newsletter name, up to three numbered expectations, and an optional sign-off. Empty items are skipped and remaining items are renumbered consecutively. Long text is truncated safely, and color-aware styling maintains readability on light and dark backgrounds.

The template is exported and registered in the newsletter category, with focused tests covering registration, rendering, item numbering, empty fields, truncation, and contrast.

How I Tested This

• npx vitest run tests/templates/welcome.test.ts passed (13 tests).
• npx vitest run tests/templates/registry.test.ts passed (8 tests).
• npx vitest run tests/templates/render.test.ts -t "newsletter-welcome" passed.
• npm run check passed (0 errors, 0 warnings).
• npm run build passed.

AI Assistance

none

Type of Change

• Bug fix
• New template
• New feature
• Documentation
• Tests
• Refactoring
• Performance improvement
• Other (describe below)

Screenshots

Checklist

• This PR targets dev
• I was assigned the linked issue
• npm run check passes
• npm run test passes
• For a bug fix: the new test fails without my change
• Tested locally with npm run dev
• Screenshots included for visual changes
• New templates follow the [Template Guidelines](https://github.com/codercops/ogcops/blob/dev/CONTRIBUTING.md#template-guidelines)

[anurag629]

Thanks @bhushan4work, this works. Check, all 1302 tests and the build pass on top of dev, and the renders look right: default, a white background with a pale accent, a long name with long items, and blank items that renumber with the sign-off hidden.